The commercial evolution of water beds has moved from the original fluid filled bag surrounded by a rigid frame of wood to relatively complex hybrid structures which combine conventional mattress foundations and frames with a lighter weight "water bed mattress". Such a mattress typically is constructed in several pieces, including a supporting border of cushioned foam or other reinforcement materials, protective liners, covers and a smaller sealed bladder filled with water. The mattress also often includes heating elements and can also be provided with vibrator assemblies.
As water beds have become accepted by a greater segment of the population, more attention has been paid to one inherent property of a liquid-filled flexible container which has become both an asset and a liability in water bed design. This property is the tendency of the filled liquid bladder to transmit reflective wave motions across the mattress. This has been countered by the inclusion of various types of baffles within the bladders of both conventional water beds and hybrid structures. The baffles attempt to reduce wave motion while maintaining the desired body support peculiar to suspension upon the surface of a body of viscous liquid. The baffled construction is commonly termed a "waveless" water bed.
A recent development in "waveless" water bed construction is the inclusion of an open celled foam filling within the interior of the water bladder. The open cell foam essentially presents thousands of irregular "baffles" throughout the bladder to resist water movement or waves. An extremely soft foam material can be utilized, making the foam itself not discernable to the user and producing a resulting bladder having the feel of a simple liquid-filled flexible bag.
This foam-filled bladder provides significant improvement in eliminating wave motion. However, the foam filled liquid bladders for hybrid bed construction still require peripheral support, special covers and the other structural components and complexities which have been typically part of the design of hybrid water beds. The separate manufacture of these components, their separate handling from the manufacturer to the consumer, and the appearance of a complex bedding structure are all believed to detract from the cost efficiency and saleability of hybrid water beds.
The average consumer is familiar with the conventional mattress--a one piece element which is generally trouble-free during its normal life. The same appearance and unitary nature would enhance acceptance of a water bed. It is also highly desirable to package a water bed mattress in a weight and size configuration compatable with the dimensions of normal bedding materials, such as sheets, blankets and bed spreads. This increases the saleability of the product by permitting the mattress to be used with other bedding items either owned by or readily available to the consumer.
According to this invention, the design gap between the structure and appearance of a conventional mattress and the recognized shortcomings of a water bed mattress is filled by constructing the water bed mattress as a unitary sealed enclosure that incorporates a peripheral self-supporting rim of foam as well as a central cavity filled with open celled foam that acts as a wave baffle. Both the side structural elements of the mattress and the wave baffle structure are immersed in water or other suitable liquid. Only the unitary bladder structure containing these interior elements is required as the basic structure within a mattress assembly. It is comparable to the innerspring assembly or foam within a conventional mattress. The sealed enclosure can be incorporated within outer cushioned covers, or can be handled and packaged separately as a mattress sub-combination.